What can you do if your grandson's mother has custody but the boy has been taken from her for neglect for the majority of his two-year life?

File a petition in family court for legal guardianship. The best option would be to have an attorney handle the matter, as custody cases can become very complexed and emotional. Also an attorney specialzing in family law is more adept at gathering substantiating evidence to prove the mother is an unfit parent. Such as procuring documents from social services and obtaining credible witnesses if necessary.